Why is a perpetual motion machine impossible?

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In the course of history, more than once ideas have arisen for engines that would give more energy than they received. Indeed, if such an engine could be invented, a very large part of humanity’s problems could be solved. However, all attempts to create a perpetual motion machine were unsuccessful. In this article I will consider several of the most typical models of perpetual motion machines, as well as the fundamental reasons that make perpetual motion machines in principle impossible.

For the first time a perpetual motion machine was proposed in the 12th century, in India by the mathematician Bhaskara II. He suggested making special containers with mercury inside the wheel.

According to his idea, in one part of the wheel, the overflowing mercury will always outweigh the mercury in the other half of the wheel, and thus the wheel will constantly rotate.

The idea of Bhaskara II has been modified more than once, for example, replacing mercury with balls, levers, weights, etc. however, the essence remained the same. Perpetual motion was to be achieved by the constant imbalance of the two parts of the wheel.

However, all such «perpetual motion machines» eventually turned out to be inoperative. The problem was that with an unequal weight of various parts of the wheel, its center of gravity also shifted, which ultimately, at some point, led to a stop of the wheel in the equilibrium position relative to the new center of gravity.

Fundamentally different is the idea of a perpetual motion machine based on magnets, as shown in the picture above. According to the idea of its authors, the magnet located at the top will drag the metal ball up the hill, then the ball will fall into the hole, roll down and again will be pulled up the hill. And so on ad infinitum.

In reality, such an engine is also inoperative. Calculations showing its inoperability are beyond the scope of this article, I will just say that there are two main scenarios. Or the magnet will not be able to drag the ball up, and if it can, then the ball will not fall into the hole, but will be attracted to the magnet.

Exposing the magnetic «perpetual motion machine»

More recently, a lot of videos with a different version of the magnetic perpetual motion machine have recently appeared on YouTube. Pieces of metal were fixed on the fan blades and when the magnet approached, the video clearly shows that the blades begin to rotate rapidly.

Such motors are impressive, but they are a simple deception: a battery is hidden under the fan edge, and the approach of a magnet only closes the contact between the battery and the fan motor.

Such «perpetual motion machines» refer to

Any such engine can only work if it has an external power source. If a working «perpetual motion machine» is demonstrated somewhere, it means that, as in the case of a fan, a battery or other source of energy is hidden somewhere.

There are also so-called

Such motors do not really violate the law of conservation of energy. But they contradict another no less fundamental physical law — the second law of thermodynamics.

The problem is that it is impossible to create a motor that converts all energy into work without loss. All the same, part of the energy will be spent on processes inside the engine (at least, for example, due to friction of engine parts against each other).

As a child, I myself tried to build such a «perpetual motion machine» according to the following scheme: the battery drives the electric motor, the electric motor rotates the handle of the generator, and the generator charges the battery. Of course, nothing worked out for me, since the energy losses were too great.

At the moment, practically no country in the world is considering new applications for the creation of perpetual motion machines, since it has long been established that such devices are theoretically impossible and the only question is where the author was mistaken.

At the same time, the progress of physics and chemistry, especially in recent years, is simply enormous and there are various promising developments that may in the future lead to the emergence of sources of «free» energy (thermonuclear fusion, vacuum energy, etc.). However, one must understand that these devices will not be «perpetual motion machines» in the classical sense of the word and will still receive energy from external sources.